Mounted stop-nuts



Sept. 4, 1956 E. A. ERICSON MOUNTED STOP-NUTS Filed March 16, 1953 [27 van 23-02:

n 0 y E W AX m M 5 M if threaded too far into the insert.

United States Patent MOUNTED STOP-NUTS Eric A. Ericson, Plainville, Conn., assignor to General Electric Company, a corporation of New York Application March 16, 1953, Serial No. 342,633

2 Claims. (Cl. 200-168) My invention relates to threaded bolt-receiving stopnuts, and more particularly to a nut of such character mounted in a molded plastic body or other mass of frangible material to receive a connecting bolt.

It is frequently necessary to provide threaded bolt holes in bodies of molded plastic insulating material or other frangible material, either to provide means for bolting another member, such as a cover plate, to the body or to provide means for attaching the body itself to a support, such as a mounting panel.

Specifically, electric circuit breakers having molded plastic cases are often mounted in this manner on supporting panels. In such plastic bodies bolt-receiving means have heretofore been formed by molding threaded tubular metal inserts into the body of plastic material.

Such molded inserts are objectionably expensive, and, unless cup-shaped they provide no stop for preventing excessively long bolts from splitting or cracking the plastic 7 Nuts have also been mounted on metal plates or the like, with the plate fixed in the plastic body and the nut loosely positioned in a recess in the plastic, but these nuts also permit cracking of the plastic by bolts of excessive length. Moreover, such inserts and mounted bolts do not possess any self-locking properties. I have found particularly that, where circuit breakers assembled in plastic cases are mounted in hazardous locations, such as in locations exposed to explosive atmospheres, the danger of cracked casings is serious because of the likelihood of gas ignition by contact sparking.

Accordingly, therefore, it is a general object of my invention to provide a mounted stop-nut which is simple in construction, reliable in operation and of low cost.

It is a further object of my invention to provide a self-locking stop-nut so constructed that, when mounted loosely in a body of molded plastic or other frangible material, it protects the frangible body against cracking by bolts of excessive length.

It is a more specific object of my invention to provide a self-locking stop-nut adapted to be mounted loosely in circuit breaker casings of molded plastic insulating material to provide for attaching of the casing to mounting panels or the like, without cracking under excessive bolt pressure.

My invention itself will be more fully understood and its various objects and advantages further appreciated by referring now to the following detailed specification taken in conjunction with the accompanying drawing, in which Fig. 1 is a side elevational view, partly in section, showing an electric circuit breaker mounted upon a supporting panel by means of a stop-nut embodying my invention; Fig. 2 is a fragmentary exploded perspective View of the stop-nut and its cooperating casing parts; Fig. 3 is an enlarged detail View in sections of the panel circuit breaker and mounting nut shown at Fig. 1; and Fig. 4 is a perspective view of a modified stop-nut embodying my invention in another form.

Referring now to the drawing, 1 have shown a circuit "ice 2 breaker 1 having a molded plastic casing 2 and a side cover 3 (one corner of which is shown broken away) mounted upon a supporting panel 4 With an actuating button 5 for the breaker protruding through the panel. The circuit breaker casing 2 is provided at each forward corner adjacent the mounting panel 4 with a nut-receiving aperture 6 (only one of which is shown) open at the side adjacent the cover plate 3 and also open at the forward end (i. e., the end adjacent the panel 4). The forward end of the circuit breaker is provided with a metal cover plate 7 having U-shaped return-bent end portions 7a closing the apertures 6 on the forward side. While the mounting details are shown for only one corner of the breaker to simplify the illustration, it will be understood by those skilled in the art that both the upper and the lower corners forward of the breaker 1 adjacent the panel 4 are of similar construction.

The return bent end portion of the metal cover plate 7 is of reduced Width and, when assembled, is held in position between a protruding shoulder 2a on the casing 2 at one side of the aperture 6 and a cooperating shoulder 3a (Fig. l) on the side cover 3. This return bent end portion of reduced width is provided with aligned keyhole apertures 7b and 7c in its upper and lower walls respectively, in which is fixedly mounted a self-locking stop-nut 8 which is loosely positioned within the recess 6.

The stop-nut 8 is formed of a U-shaped band of metal having its side portions offset inwardly into flatwise engagement for an appreciable portion of their length adjacent the free ends thereof, as at 9, Fig. 2. The lower or diverging ends of the side portions of the nut 8 are cut away or apertured at 10 and 11. The juxtaposed side portions 9 are oppositely spread out in semi-cylindrical shape intermediate their side edges, as at 12, and are threaded internally at 13 to form cooperating halves of a cylindrical bolt-receiving nut. The upper or free ends of the juxtaposed side portions are provided with two juxtaposed pairs of extending tabs 14 and 15 of reduced section forming shoulders 16 and 17 respectively, at the free ends of the side portions of the nut.

As shown at Figs. 1 and 3, the juxtaposed or engaging side portions 9 of the nut 8 are positioned within the aligned keyhole apertures 7b and 7c with the tabs 14 and 15 extending through the upper aperture 7b. For this purpose the aperture 7b is slightly shorter than the aperture 70, so that the upper wall of the mounting plate 7 seats upon the shoulders 16 and 17. The tabs 14 and 15 are peened over the plate 7, as shown at Fig. 3, to attach the nut 8 to the plate.

In assembling the mounted nut described above, it is preferable to insert the U-shaped member 8 into the apertures 7b and 7c of the plate 7 before tapping the nuts. With the member 8 inserted into the plate 7 and the tabs 14 and 15 peened over, the semi-cylindrical portions 12 are tapped, and in this operation the die will spread the lower ends of the semi-cylindrical portions 12 as it approaches the end of the thread. When the die is withdrawn, the juxtaposed side portions of the nut 8 spring together into their original shape and thereby are prepared to exert a resilient clamping action upon a mounting bolt 18 later threaded therein. To facilitate this resilient clamping action, the keyhole slot 7c is made slightly over sized for the nut.

It will now be understood by those skilled in the art that, with the nut 8 thus fixedly mounted in the plate 7, the assembled plate with the nuts at each end is slipped sideways onto the circuit breaker casing 2 to position the nuts loosely within the apertures 6. As shown at Figs. 1, 2 and 3 the return-bent end portions 7a of the plate 7 slip under shoulders 20 on the casing 2 to position and hold the plate. The side cover 3 is then placed upon the circuit breaker and fixed in position to prevent removal of the plate 7.

' (:1 It Will'befurther evident that, when the mounting bolts 18, by--which the circuit breaker is fixed -to -the panel- 4,- v are threaded into the 8, contact between the bolt and the frangible plastic casing is prevented by the bight portion of the nut. Thus, even 'though an oversized ,bolt is threaded too far; into the nut, no-damage can be done to the frangible casing. b

-At Fig. 4*I-have shown a modified form 'of se lf locking stop-nut 8 in Whichthe semi-cylindrical;cooperating side portions'iZ of the nut are provided With depending internally threaded tabs 12 extending downwardly into the apertures "10 and 11 to provideadditional clamping force tolock a cooperating bolt-in position. 'It Willbe evident that'these arcuate tabs 12' (only onejofwhichis shown) may be pinchedtogether after tapping, thereby to'increas'e the clamping force uponla cooperating'bolt.

'While I have shown onlycertain-preferred embodiments of my'invention by way of illustration, many modifications will occur'to those skilledin the art, andlitherefore Wish to'have it understood that'I intend'in the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claimas new and desire to secure by Letters Patent of the United States'is:

1. A mountedstop-nut comprising a U-shaped band'of metal having its side portions oifset inwardly into fiatwise engaging relation for an appreciable portion of their length adjacent their free ends, and angularly diverging adjacent the bight of said U-shaped band, the said diverging portions of said sides'being centrally apertured and the juxtaposed ends of said side portions beingsemicylindrical intermediate their side edges and threaded internallylthroughout the complete length of said engaging portionsto constitute complementary halves of a bolt-receiving nut saidside portions having integral locking portions adapted to be engaged and forced apart by a bolt threaded between said side portions Whereby'to provide a resilient lockirigbpressure resisting loosening of said bolt, two pairs oftabs of reduced section extending from the free ends of said engaging side portions and forming shoulders at the ends of said side portions, and a mounting plate having a keyhole aperture seated upon said shoulders to hold said free ends of said side portions infixed relativeposition,

'said tabs being peened over 7 -ture to secure -said nut to --said plate.

2. In combination, a body of frangible molded plastic material having a recess therein, .a metal'plate having a return bent end portion tilted to said body with said end portion closing said aperture at one side, said return bent end portion having spaced apart Walls provided with aligned keyhole apertures therein, a U-shaped stop-nut loosely positioned insaid recess andghaving its side por-- a resilient locking'pressure resisting loosening of said bolt,

and tabs of reducedsection extending-from-saidrfree ends of .said side portionsand peened over said mounting plate to secure-said nut to said plate to hold said'free ends in fixed-relative position thekeyhole aperture in said returnbent end portion of said plate adjacentthe bight of said U shaped stop-nut being slightly-oversize with respect to the portion of saidstop-nut passing therethroughwhereby said side portions'may move a limited amount with respect to each otherto resiliently grip a'bolt insertedtherein.

' "References-Cited in the file of this patent LUNITED STATES :PATENTS said plate through said aper- 

